Suppressing Halide Segregation Via Dual‐Anchoring Strategy for 31.20% Perovskite/Silicon Tandem Solar Cells

Abstract The efficiency and stability of wide bandgap (WBG) perovskite solar cells (PSCs) are constrained by photo‐induced halide segregation and severe non‐radiative recombination, which significantly impedes the advancement of high‐efficiency and stable perovskite/silicon tandem solar cells (PSTSCs). In this work, a potassium 4‐sulfonic‐1,8‐naphthalic anhydride salt (4S‐NAPS), featuring dual‐anchoring sites, is incorporated into the perovskite precursor. The sulfonic group (─SO 3 − ) and carbonyl group (C═O) interact with uncoordinated Pb 2+ ions on the perovskite surface. In addition, K⁺ ions occupy interstitial sites within the crystal lattice, thereby effectively enhancing the ion migration barrier and suppressing halide phase separation. Owing to the dual‐anchoring effect of 4S‐NAPS, a single‐junction WBG PSC (1.68 eV) delivers a power conversion efficiency (PCE) of 22.95% and an open‐circuit voltage (V OC ) of 1.26 V, representing one of the highest efficiencies reported for WBG PSCs. Moreover, the unencapsulated modified devices retain 90% of initial efficiency after 3000 h in a nitrogen atmosphere, demonstrating remarkable operational stability. Notably, the fabricated monolithic PSTSC achieves a PCE of 31.20%, a V OC of 1.950 V, and exhibits negligible hysteresis. This dual‐anchoring strategy provides a promising avenue for fabricating highly efficient and stable WBG PSCs and offers new insights into achieving superior performance in PSTSCs.